1. Field of the Invention
The present invention relates to a far-infrared radiation image processing apparatus, a far-infrared radiation imaging apparatus, a far-infrared radiation image processing method, and a far-infrared radiation image processing program. More particularly, the invention relates to a far-infrared radiation image processing apparatus, a far-infrared radiation imaging apparatus, a far-infrared radiation image processing method, and a far-infrared radiation image processing program for processing far-infrared radiation images taken by detecting far-infrared rays radiated from objects.
2. Description of the Related Art
There exist far-infrared radiation imaging apparatuses, a type of equipment for thermography whereby a given object is imaged using a far-infrared radiation sensor to measure the temperatures of the object being imaged. The far-infrared radiation sensor is typically made up of picture elements such as pyroelectric elements or bolometers capable of detecting the energy (heat) from the far-infrared rays being radiated by the imaged object.
When an image of the object is taken by the above type of far-infrared radiation imaging apparatus, the image is constituted by pixels. If the actually output pixels have numerically large increments, then the resolution of the output values drops unless the range of gray-scale levels is enlarged for representing the measurements in image form. Conversely, if the resolution is increased with the gray-scale range kept unchanged, then the range of the temperatures that can be displayed is narrowed. For example, if a far-infrared radiation image taken by a far-infrared radiation camera in increments of 0.05° C. is displayed on a 256-level gray-scale monitor, then the maximum difference between the lowest and the highest temperatures that can be displayed is mere 12.8° C.
There have been proposed infrared radiation temperature measuring apparatuses such as one disclosed in Japanese Patent Laid-Open No. Hei 07-035621, referred to as the Patent Document 1 hereunder. This type of apparatus displays an infrared radiation image taken by an infrared radiation camera to indicate temperature information about a given object. When a given spot of the displayed image is designated, the apparatus displays the temperature corresponding to the designated spot.
Also proposed are far-infrared radiation image displaying apparatuses such as one disclosed in Japanese Patent Laid-Open No. Hei 07-239271, referred to as the Patent Document 2 hereunder. Where calculated data fails to fill a full-scale data range, this type of apparatus performs bit shift operations to create image display data with as many bits as requested by a signal processing section of the apparatus.
There have been proposed imaging apparatuses such as one disclosed in Japanese Patent Laid-Open No. 2000-074741, referred to as the Patent Document 3 hereunder. Where a low-illumination object and a high-illumination object coexist within a single frame, this type of apparatus offsets the signal levels involved and suitably controls their amplification factors.
Further proposed are far-infrared radiation camera systems such as one disclosed in Japanese Patent Laid-Open No. 2003-344167, referred to as the Patent Document 4 hereunder. Based on the relative temperature distribution of an image signal which is proportionate to the temperatures of an object radiating infrared rays, this type of apparatus narrows the range of the temperatures at low concentrations so as to highlight temperature resolution selectively.